Linear motor facsimile machine

ABSTRACT

The present invention provides a multi-purpose facsimile machine which functions as either a telecopier or a photocopier, at the selection of the user. The machine, when used as a telecopier, eliminates synchronization of transmitting and receiving units by storing transmitted data in a memory prior to printing. The facsimile machine includes a linear motor for driving both a print head and scan head on a single block. The linear motor includes at least one electrical coil driven along at least one lateral guide member formed from interspersed magnetic and non-magnetic materials. By selectively energizing the coil, the motor is advanced along its guide member by magnetic interactions. The electrostatic print head of the facsimile machine includes at least one thin conductive wire fused into at least one glass casing for providing a solid block structure for protecting and supporting the wire.

This is a division of application Ser. No. 390,210 filed June 21, 1982now U.S. Pat. No. 4,476,496.

BACKGROUND OF THE INVENTION

Facsimile machines, such as telecopiers which are connected to standardtelephone receivers for transmitting or receiving data over telephonelines, are generally known to the art. In the known machines,transmitting and receiving units must be synchronized to enable thereceiver to print incoming data as it is received. Known telecopierscannot be used as photocopying machines, and do not provide forsimultaneous voice and data transmissions. The known telecopiers alsouse relatively complex, and thereby expensive motors, to drive theirmoving components, such as their print or scan heads. Electrostaticprint heads used with telecopiers consist of relatively thick,unprotected free standing angled wires, which generally can print onlyin one direction and do not provide fine printing resolution.

SUMMARY OF THE INVENTION

The present invention overcomes the above-mentioned problems of theknown facsimile machines by providing a multi-purpose facsimile machinewhich functions, at the selection of the user, as either a telecopierreceiver or transmitter, or as a photocopier. Synchronization of thetransmitter and receiver, when the machine is used as a telecopier, iseliminated by a memory storage device provided in the receiver whichstores incoming data before printing. The facsimile machine enablessimultaneous data and voice transmission by transmitting voice and datasignals in two separate, mutually exclusive frequency bands.

In a further aspect of the invention, a linear motor, which can be usedto drive the scan and print heads of the facsimile machine, includes atleast one electrical coil mounted to a guide member. The guide memberincludes both magnetic and non-magnetic areas or inserts interspersedthereon in sections of predetermined length. By selectively energizingthe electrical coil, the resultant magnetic interaction between theenergized coil and the magnetic areas on the guide member, which actlike a solenoid in reverse, advances the coil along the guide member.

In a further aspect of the invention, the linear motor is used to carryan electrostatic print head, stylus and scan head in a facsimilemachine. The stylus of the print head is formed by a process in which awire or plurality of wires are encapsulated into a single solid glassrod or block. The glass encased wires are rigidly supported so thatthinner wires providing better quality printing may be used. The stylusmay be used to print in both directions of movement of the motor, may bepositioned vertically with respect to the paper to allow bi-directionalprinting and to avoid scratching the paper. The force of the wire isdistributed over the larger bottom surface area of the glass encasementto prevent tearing of the paper by the wire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings illustrates a perspective view of a facsimilemachine in accordance with the present invention;

FIG. 2 illustrates a top plan view of the machine of FIG. 1, partly insection;

FIG. 3 is a sectional view of the machine taken along directional arrows3--3 of FIG. 2;

FIG. 4 is a sectional view of the machine taken along directional arrows3--3 of FIG. 2;

FIG. 5 is a sectional view taken along directional arrows 5--5 of FIG.2;

FIG. 5A is a sectional view taken along directional arrows 5A--5A ofFIG. 5;

FIG. 6 is a sectional view taken along directional arrows 6--6 of FIG.5;

FIG. 7 is a sectional view of the machine taken along directional arrows7--7 of FIG. 2;

FIG. 7A is a block diagram of the control system of the facsimilemachine;

FIG. 8 is a diagram illustrating one possible arrangement of threelateral guide members and three corresponding coils for supporting anddriving the linear motor of the facsimile machine of the presentinvention;

FIG. 9 is a diagram illustrating a second example of an arrangement oftwo lateral guide members and three coils for supporting and driving thelinear motor of the facsimile machine the present invention;

FIG. 10-13 illustrate a method of producing a print head for thefacimile machine--or other printer, and

FIG. 14 is a sectional view, taken along directional arrows 14--14 ofFIG. 13, of a print head formed from the methods illustrated by FIGS.10-13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-7A of the drawings illustrate the preferred embodiment of afacsimile machine in accordance with the present invention; FIGS. 8-9illustrate a linear motor used to drive the print head of the facsimilemachine; and FIGS. 10-14 illustrate a method of manufacturing the printhead used in the facsimile machine. As used herein, the facsimilemachine may be a telecopier, a photocopier, or combination of both. Forconvenience, the following discussion of the drawings will besub-divided into three separate sections entitled "Facsimile Machine","Linear Motor" and "Print Head".

FACSIMILE MACHINE

The facsimile machine illustrated in FIGS. 1-7A is an apparatus forreproducing written documents. As will be developed herein, the devicecan function as a telecopier to either transmit or receive data throughconventional telephone equipment, or it may be used as a standard officephotocopier. The facsimile machine eliminates the need forsynchronization of transmitting and receiving units when it is used as atelecopier, and also provides simultaneous transmission of data andvoice signals. Moreover, complicated timing systems for scanning,printing and motor drive are eliminated by the machine.

FIG. 1 of the drawings illustrates a perspective view of the preferredembodiment of the facsimile machine. A housing 2 includes two ports 4for coupling the facsimile machine to a conventional telephone receiver.A glass plate 6 on the top surface of the housing supports a document tobe copied, which is placed face down on the glass. Beneath the glass area plurality of parallel guide tubes or rods 8, extending laterallyacross the housing for supporting a block 10 which is slideably mountedon the guide rods or tubes for lateral movement across the housing. Aswill be discussed in the section dealing specifically with the linearmotor, a plurality of interspersed magnetic and non-magnetic inserts aremounted in a predetermined pattern throughout the length of each guiderod or tube 8 for driving a linear motor mounted thereon. The block 10includes a linear motor, a scan head, and a print head, each of whichwill be discussed in greater detail below.

The block 10 and guide rods 8 are positioned within two parallelsidewalls or partitions 13 that extend in the direction of the guiderods. A film 15 extending laterally across the housing and parallel tothe guide rods is also enclosed within the partitions 13. The rods andfilm are supported by end blocks 21 perpendicular thereto, and the endblocks are supported by the partition sidewalls, as illustrated in FIGS.2 and 3.

The end of a sheet of paper 11 is shown extending from one end of thehousing 2 through a suitable slot in that housing. Preferably, the paperis a black or darkened material having an aluminum coated upper surface.As is known in the facsimile machine art, an electric voltage applied tothe aluminum coated surface of the paper, as for example, by arelatively thin electrical stylus in contact with the paper, willproduce an electric arc. The arc melts a small portion of the aluminumsurface to expose a corresponding portion of the black paper thereunder.The result is that a black dot appears. These black dots provide a copyof the written document to be reproduced.

Turning now to FIG. 2 of the drawings, it can be seen that the guiderods 8, the slideable block 10, and the film 15, are mounted in agenerally rectangular frame designated by the reference numeral 12including the two spaced, parallel sidewalls or partitions 13 shown inFIG. 1. As noted above, the block 10 is laterally movable on the guiderods between the sides of the housing 2. A conveyor system is providedto move the frame 12 longitudinally across the housing 2 beneath theglass cover 6.

The conveyor system includes two toothed side belts 14. The belts aredriven by a stepping motor 16 positioned at the rear of the housing 2,and are also coupled around a lateral guide shaft 18 at the front of thehousing. A gear drive system may be coupled to the motor 16. Two clamps20 on each belt connect the ends of the frame 12 to the belts 14 so thatthe frame is longitudinally movable across the housing, at least for thelength of the glass plate 6. As illustrated in FIGS. 3 and 7, lateralguides or spacers 62 are provided to separate the ends of the frame 12from the inner sides of the housing 2 when the frame is moved within thehousing. The frame 12 rides on wheels attached to the end blocks 21. Thewheels ride on a track mounted to sides of the housing.

Accordingly, when the frame 12 is stationary and the block 10 is movedlaterally along the guide rods 8, a print head mounted to the lowerportion of the block 10 engages the paper 11 thereunder to print a lineof information. When the line is completed, the frame 12 is advanced apredetermined distance to the right in FIG. 2 by the conveyor system,and the block 10 continues moving laterally to print another line.

As noted above, the laterally moving block 10 is driven by a linearmotor and includes an electric print head mounted beneath the motor anda scan head mounted above the motor. The motor, print head and scan headwill be discussed in greater detail below. However, FIG. 2 doesgenerally illustrate an electrical connector 22 movable with the block10, and an attached electrical cable 24, for powering the linear motor,print head, and scan head.

FIG. 2 further illustrates bumpers or shock absorbers 26 provided at theends of the respective lateral guide rods 8 to cushion the impact of theblock 10, including the linear motor, against the ends of the frame 12.Each bumper is formed from a coil spring 28 mounted around the end of aguide rod. One end of each spring is coupled to the adjacent end of theframe 12, while the other end is coupled to a stop 30 which, forexample, may be a ring mounted around the respective guide rod. The stopmay also be defined by integrally extending the spring itself. FIG. 7illustrates the shock absorbers in greater detail.

The block 10 will now be discussed in greater detail in connection withthe following discussion of FIGS. 3, 4 and 5. Referring first to FIG. 5,the block 10 carries a linear motor including three electrical coils 32,34 and 36. Each coil is mounted through its central opening, on adifferent one of three guide rods 8. As will be discussed in detail inthe section specifically describing the linear motor, means are providedto selectively energize and de-energize the three electrical coils tomove the linear motor laterally along the guide rods. Although threecoils mounted to three separate guide rods are illustrated in thedrawings, different numbers of coils and guide rods are equallyfeasible. Moreover, several coils can be mounted on the same guide rod,so that the number of coils does not necessarily have to correspond tothe number of guide rods.

A scan head, shown generally as reference numeral 38, is mounted to thetop of the linear motor. The scan head includes two light sources 40mounted on a supporting block 41. The light sources direct light at anangle towards the lower surface of the glass plate 6. A generallycylindrical aperture 42 in the block 41, is disposed between the twolight sources 40. A plurality of photodetectors, preferablyphototransistors 49 (FIG. 5A) are mounted under a window 51 in the endof cylindrical can 45 seated within aperture 42. A lens 43, mounted atopthe aperture 42, focuses light from the sources 40, which is reflectedback towards the scan head by information on a document on the glasscover 6, to the phototransistors 49 in the cylindrical can 45.Electrical leads (not shown) transmit signals generated by thephototransistors in response to the reflected light. Spacers 44 aredisposed between the top surface of the scan head and the lower surfaceof the glass 6 to provide separation between these elements when thescan head moves relative to the glass when driven by the linear motor.Springs 46 act on the lower surface of the block 41 to maintain thespacers at the top of the scan head flush against the glass 6.

A print head, shown generally by the reference numeral 48, is attachedto the lower portion of the linear motor and extends below it.Electrical wires 50 connect the print head to a power supply forelectrical energization thereof. The print head itself includes an uppersupporting member 52 fixedly mounted to the lower portion of the block10, and a lower electrical stylus 54 removably mounted within the uppersupporting member. As will be discussed in the section specificallydescribing the print head, the stylus includes a plurality ofelectrically conductive wires, the ends of these wires engaging theprinting surface of the aluminum coated paper 11. When the print head isenergized, information is printed on the paper 11. For example, thealuminized paper 11 may be grounded, and a voltage may be applied to thepaper through the stylus wires, thereby causing an electrical arc andprinting a dot, as was previously discussed. In the alternative, avoltage may be applied to the aluminized printing surface, and thestylus may be selectively grounded thereby causing an electrical arc andprinting a dot. In either case, actuation of the stylus causes theprinting of a dot corresponding to information on documents to bereproduced.

The film 15 extending laterally across the housing 2 (see FIG. 1) isillustrated in FIG. 5. As shown, two light sources 56 are disposed onone side of the film, while two corresponding light detectors aredisposed in alignment with the light sources on the opposite side of thefilm 15. The light sources 56 and the corresponding light detectors 58are movable with the linear motor, print head, and scan head on theblock 10, while the film 15 is mounted stationary in the housing 2, asillustrated in FIG. 1.

The sources 56, the detectors 58 and the film 15 comprise a timingfence, as will be discussed below, for controlling the spacing ofprinting on the paper 11, for controlling the positions at which thescan head reads a document to be copied from the glass 6, and forcontrolling the actuation of the linear motor. The film 15 includes aclear sheet of material having a plurality of tick marks or darkenedspots applied at predetermined spaced intervals along the length of thefilm. Preferably, each mark is spaced 0.014 inch apart from the nextmark, and two sets of marks offset from each other by 90° are providedon the film, as illustrated by FIG. 6. The marking pattern shown in FIG.6 is known in the art as QUADRATURE. A second strip of film 15A isattached to the light sources and is movable with the block 10 so thatmotion is detected by the moire effect.

FIG. 7 illustrates in greater detail the lateral spacers shown generallyas reference numeral 62 in FIG. 3 and the shock absorbers 26, previouslydiscussed with respect to FIG. 2. The spacers include a spacing elementor lateral guide 62 affixed to the end blocks 21 of the frame 12. As theframe 12 is moved within the housing 2, the lateral guide 62 moves alongan end 66 of the housing 2. The spacers assure at least a predeterminedclearance between the frame end blocks 21 and the housing end 66 tofacilitate movement of the frame relative to the housing as discussedwith respect to FIG. 2. FIG. 7 also illustrates a gear wheel 64 whichengages the toothed side belts 14 for moving the frame 12 relative tothe ends 66 of the machine housing 2. As discussed above, the wheels onthe end blocks 21 engage trackes defined on the sides 66 of the housing2 to provide the relative movement.

In operation of the facsimile machine, the linear motor is energized todrive the block 10 along the lateral guide rods 8. (The operation of thelinear motor itself will be discussed separately below.) The lightsources on the scan head are directed towards a document on the upperglass cover to be reproduced. Information on the document reflects thelight through the lens 43 towards the phototransistors in the scan head,and the phototransistors generate an information signal. Eachphototransistor monitors a different area in the field of view of theportion of the document being scanned. As the linear motor traverses thelateral guide rods 8, the light sources and photodetectors 56 and 58 ofthe timing fence (FIG. 5) move along the stationary film 15. As thesources pass the darkened spots or tick marks on the film, the lightfrom the source is not sensed by its respective detector. Acorresponding signal is generated by the timing fence.

The signals generated by the detection of information and by the timingfence, as described above, are transmitted to a memory storage device asshown in FIG. 7A. In the preferred embodiment of the invention, thememory is provided by a microcomputer. The information signals generatedby the phototransistors 49 are transmitted to the memory storage deviceby phototransistor electrical leads.

FIG. 7A is a block diagram illustrating the control circuitry of thefacsimile machine discussed herein. As discussed above, the tick markson the film 15 are spaced apart from each other by a predetermineddistance. A signal generated by the timing fence (when its sources anddetectors pass a tick mark on the film 15) is transmitted to a memorystorage device, which samples a signal from the scan head. The scan headis energized and scans the information on a document (on glass 6) withinits field of view. The information is transmitted back to the memorystorage with appropriate signals for indicating the beginning and end ofeach line of information scanned.

A signal from the timing fence to the memory storage also generates asecond signal from the memory storage device to the print head,resulting in the printing of information previously read by the scanhead and already stored in the memory. Because signals from the timingfence are only generated at predetermined intervals, information printedby the print head will be spaced apart a distance corresponding to thepredetermined intervals.

A third signal is transmitted from the memory storage to the linearmotor when the memory storage receives a signal from the timing fence.This third signal is used to drive the motor, as will be more fullydiscussed in the section describing the motor.

The memory storage is also coupled to the stepping motor 16 (FIG. 2) tocontrol the movement of the carriage assembly relative to the printingsurface to assure that the print head only prints information within apredetermined vertical range (Y axis) on the printing surface.

Accordingly, the timing fence assures that the scan head will scaninformation at predetermined distance intervals, that the printer willprint information spaced apart at predetermined distance intervals, andthat components of the linear motor will be activated or deactivatedonly at predetermined positions on the guide rods supporting the motor.The timing fence continually monitors the position of the motor relativeto the guide rods, and transmits this information to the memory.

It is apparent that the use of the timing fence eliminates the need fora complex timing system, dependent on the speed of the linear motor.That is, the scanning and printing operations are dependent only on theposition of the linear motor as detected by the timing fence, and arenot dependent on the speed of that motor. To the contrary, a systemdependent on motor speed requires complex means for compensating forvariations in motor speed.

The facsimile machine of the present invention may also be used as areceiver or transmitter for a telecopier machine in addition to its useas a photocopier as described above. When transmitting information, adocument is scanned, as discussed above, and information is transmittedto the memory storage. However, the information is subsequently providedto a transmitter for transmission over telephone lines. Although notnecessary, if it is desired, the transmitted information may also beprinted at the transmitting unit in the manner described above.

A receiver is provided for receiving transmitted information from aremote transmitter when the facsimile machine is operating as atelecopier receiver. Information received at the receiver is transmittedto the memory storage device, and thereafter printed as described above.When in use as a telecopier receiver, the scanning operation of thefacsimile machine is unnecessary.

Accordingly, the present facsimile machine is a multi-purpose apparatuswhich can be used selectively as a photocopier of documents, atelecopier machine transmitter, or a telecopier machine receiver. Whenused as a telecopier machine, the device advantageously eliminates theneed for mechanical synchronization between transmitting and receivingunits. As a receiver, the machine stores received information in amemory storage. The information can be printed thereafter. There is noneed to print the information simultaneously as it is received, as isdone in many known telecopier machines. Likewise, information to betransmitted is first stored in the memory storage device. It maythereafter be transmitted to a remote receiver, However, there is norequirement that the information be transmitted simultaneously with thescanning of a document to be copied.

The present invention further contemplates a method of simultaneousvoice and data transmission when the facsimile machine is used as atelecopier machine. A standard telephone line provides a frequency rangeof 50-3000 Hz. By transmitting all data information in a band range of2000-3000 Hz, while transmitting all voice signals in a band range50-1900 Hz, simultaneous data and voice transmissions over the sametelephone line is possible. Conventional filters may be used to assurethat the data and voice signals are within their separate bands. The useof simultaneous voice and data transmission provides a significantconvenience to the user.

In summary, the facsimile machine of the present invention provides amulti-purpose apparatus which may be used, at the selection of the user,as a photocopier, or a telecopier receiver or transmitter. The apparatusincludes means for eliminating the need to synchronize telecopierreceivers and transmitters, and further provides simultaneous voice anddata transmission. Moreover, a photoelectric system dependent on theposition of a motor, and independent of motor speed, assures that themachine will scan at predetermined locations within the machine and allprinted information will be printed at predetermined intervals,regardless of motor speed.

LINEAR MOTOR

The operation of the linear motor of the present invention will now bediscussed with reference to FIGS. 8 and 9 of the drawings. As discussedabove, the linear motor may be used to drive the print head of thefacsimile machine in both directions of traverse across a printingsurface. When used in this manner, the linear motor is supported byguide members 8, shown in FIGS. 1-7, which may be either rods or tubes.

The linear motor, shown generally as part of block 10 in FIGS. 1, 3 and4, includes a plurality of electrical coils 32, 34 and 36 mounted onbobbins in a motor housing. Preferably, the bobbins are attached to thehousing with steel brackets. The housing itself is mounted on theplurality of lateral guide rods or tubes 8 above a printing surface andextending in the same direction as that surface. The housing issupported by the bobbins riding on the rods or tubes 8. A print head 52(FIGS. 4 and 5) mounted under the linear motor is driven by the motorlaterally along the guide members 8 so that the pri-nting stylus 54 ofthe print head contacts the printing surface 11.

FIG. 8 diagrammatically illustrates the arrangement of the guide membersand coils of the motor used in the embodiment of the invention discussedin FIGS. 1-7. The motor housing is mounted on three guide rods 8 suchthat each of three electrical coils 32, 34 and 36 is positioned on adifferent one of the guide rods.

Magnetic material or inserts 68 and non-magnetic spacers 70 are mountedto the guide rods or tubes 8 throughout their entire length. Themagnetic inserts may be, for example, iron slugs while the spacers maybe aluminum slugs. Means are provided to selectively electricallyenergize and de-energize the individual coils mounted to the guidemembers 8, thereby providing a magnetic interaction between an energizedcoil and one of the magnetic areas on the guide member supporting therespective coil. Actuating an electrical coil as the coil approaches amagnetic area or strip on its guide member will result in a magneticattraction advancing the coil towards the center of the magnetic area.The electrical coil and magnetic insert act as a solenoid in reverse.Thereafter, that coil may be de-energized and another coil energizedsuch that the other coil will advance, as a result of magneticinteraction, towards the center of the next forward magnetic area on itsrespective guide member. By selectively energizing and de-energizing theindividual electrical coils in dependence upon their position relativeto the magnetic areas on the respective guide members, the motor housing(and the print head and scan head carried thereby), are advancedlaterally across the housing 2 from one end of the guide members to theother. By reversing the phase pattern applied to the coils, the motorcan be returned to its initial starting position at the other end of theguide members 8.

In effect, the coils of the linear motor and the magnetic inserts on theguide members act as solenoids in reverse. Preferably, the length of themagnetic areas defined on the guide members will be two times the activelengths of the coil mounted to the respective guide member. Also, it ispreferable that the length of non-magnetic areas be slightly less thanthe length of the motor housing so that at least one coil will beadjacent to a magnetic area at any point along the guide member. Byconforming the length of the non-magnetic spacers to the aboverequirement, start-up of the motor is guaranteed at any position on thelateral guide members.

Energization and de-energization of the coils may be accomplished by useof any of several conventional means. For example, a photodetectionsystem can be used to provide signals to actuate or deactuate coils asthey traverse certain predetermined positions on the guide members. Inthe alternative, a computer may be programmed to actuate and deactuatethe coils at the proper respective locations on the guide members.

When the linear motor is used to drive the print head and scan head ofthe facsimile machine described herein, the selective energization andde-energization of the coils 32, 34 and 36 necessary to drive the coilsacross the lateral guide members 8 may be provided by the microcomputerdevice shown in FIG. 7A. As discussed above, signals from the timingfence transmitted to the microcomputer device indicate the position ofthe linear motor relative to the guide members. The memory may beprogrammed to provide signals for actuating and deactuating the propercoils at the proper positions on the guide members to provide thenecessary linear motion.

FIG. 9 illustrates a second possible arrangement of the linear motorincorporating two guide members 8 and three coils, 32, 34 and 36, two ofwhich are mounted apart from each other on the same guide member. Asdiscussed above, the motor linearly traverses the guide members byselectively energizing and de-energizing the individual coils dependingon their respective positions relative to the magnetic areas of theirrespective guide members.

It is apparent that the linear motor described above includes only aminimal amount of moving parts, does not require permanent magnets, andthus can be produced inexpensively. The guide member serve a dualfunction, both supporting and guiding the motor, and also driving themotor. The motor is efficient and converts electric energy intotranslational motion via a magnetic interaction.

The arrangements of the linear motor illustrated in FIGS. 8 and 9 areillustrative only since numerous other variations and arrangements usingthe basic principles described herein are possible. Moreover, the linearmotor may be used in addition to driving the print head and scan head ofthe facsimile machine described herein, in a wide variety ofapplications such as with standard printers, photocopiers, typewritersand other apparatus in which linear motors are required. That is, thelinear motor is not limited to use in the specific facsimile machinedescribed herein.

PRINT HEAD

FIGS. 10-14 illustrate a method of manufacturing a print head of thetype used in the facsimile machine of the present invention. The printhead is also suitable for various other printing operations notnecessarily connected with the facsimile machine. As already discussedherein, electrical energization of the print head melts a portion of analuminum coating on a printing surface to expose or print a dot.

As illustrated in FIG. 10, three thin electrically conductive wires 72,74 and 76, are stretched tightly across a jig or rack generallydesignated by reference numeral 78. One end of each of the three wiresis clamped to the jig, while a weight 80 is attached to the other endsof the wires extending beyond the jig. The weight keeps the wiresstretched tightly across the jig. Preferably, the wires are each formedfrom tungsten and are each approximately in the range of 2-10 mils indiameter, preferably about 5 mils.

A first hollow glass cylinder or tube 82 includes three smaller hollowglass cylinders or capillary tubes 84, 86 and 88 removably receivedtherein. Each of the three wires 72, 74 and 76 is threaded through adifferent one of the smaller glass tubes, and the larger cylinder 82 isslid over the three smaller tubes before the weight 80 is attached tothe wire ends. The three smaller tubes initially are slideable alongtheir respective wires, and the larger amd smaller tubes are positionedtowards one end of the jig as shown in FIG. 10. The exposed- portions ofthe wires 72, 74 and 76 are then annealed and oxidized by continuouslyheating them with a torch 90.

Once the wires have been annealed, each smaller tube 84, 86 and 88 isslid out of the larger tube 82 and positioned on the exposed portion ofits respective wire, as illustrated in FIG. 11. The smaller tubes arethen individually heat fused by the torch 90 to the respective wires.Thereafter, as shown in FIG. 12, the larger glass tube 82 is slid alongthe three wires and over the three smaller tubes, each of which alreadyhas been fused to a different one of wires 72, 74 and 76. The largertube 82 is then itself heat fused to the outer surfaces of the smallertubes by the torch 90.

The weight 80 attached to the ends of the three wires 72, 74 and 76 isremoved, while the other ends of the wires are unclamped from the jig78. Thereafter, the fused tube is cut or sawed in half at itsapproximate longitudinal center by a saw 92 as illustrated in FIG. 13,and the cut end surfaces of that tube are polished.

FIG. 14 is a sectional view through one of the cut halves of the largerglass tube 82. Each half includes the three smaller tubes 84, 86 and 88embedded or encapsulated in the larger tube 82. The individual wires 72,74 and 76 are themselves each encapsulated in a different one of theirrespective smaller tubes.

The process described above results in the production of two separateencapsulated, solid rod or block print heads since each half of the cutlarger tube 82 can be used as a print head. The ends of the wiresextending from the far ends of each cut half (FIG. 13) may be coupled toa suitable electric source, while the wire ends terminating at the cutsurfaces contact a printing surface to print information thereon.

When the print head is used with the facsimile machine illustrated inFIGS. 1-7A, the wires extending from the far ends of the encapsulatedblock are coupled to the microcomputer of FIG. 7A. The computer controlsthe energization of each wire to control the printing of dots onprinting surface 11. Each wire of the stylus corresponds to the field ofview scanned by one phototransistor 49. Printing of dots by the stylusof the print head is controlled by the microcomputer device in responseto information signals received from the scan head, as alreadydiscussed.

Preferably, the diameters of the smaller tubes are each about 0.01" andthe diameter of the larger tube is about 0.1". In this manner, thesurface area of the three 5 mil wire ends is only approximately 15% ofthe sectional surface area of the entire encapsulated print head.Although the print head produced from the process described aboveincludes three wires, a print head having any number of wires may beformed similarly from the same procedure.

The encapsulated, solid block print head, as illustrated in FIGS. 13 and14, incorporates several advantages over known print heads whichgenerally use free-standing wires. By encapsulating the wires of theprint head, these wires are reinforced and strengthened. Accordingly,the wires may be formed from very small diameter, fine conductivematerial such as 5 mil diameter tungsten, thereby providing finerresolution of the printed information. To the contrary free-standingwires must be self-supporting and thereby are formed from relativelythick, durable conductors. Increasing the thickness of the wirescorrespondingly decreases the fineness of the resolution of the printedinformation.

Further, by encapsulating the wires of the print head, wear and tear onthe wires is decreased, thereby extending the useful life of the printhead.

Moreover, the end of the print head may be substantially perpendicularto the printing surface, which is not possible with a free-standingwire. A free-standing wire tends to be bent or angled at the end of thewire contacting the printing surface. Therefore, print heads includingfree-standing wires generally print only in one direction of movement;namely, in the direction of the bend at the end of the wire. Such printheads are removed from contact with the printing surface on the returnto its starting position because printing against the bend in the wiremight cause the wire to tear the printing surface. However, byencapsulating the wire in a supporting structure with only a relativelysmall portion of the wire end extending from the printing end of theprint head, the print head and wire may be maintained substantiallyperpendicular to the printing surface without any resultant bending ofthe wire. Therefore, the print head may be used to print in bothdirections, without damaging the printing surface.

As previously mentioned, the surface area of the encapsulated wire endsis only a relatively small percentage of the total cross-sectional areaof the larger tube 82 (FIG. 14). Therefore any force exerted on theprint head to maintain it in contact with the printing surface is notapplied only to the wires, but distribution of the force over thecross-sectional area of the larger tube reduces the stress on the wires,thereby increasing their useful life. To the contrary, in a print headformed from free-standing wires, all of the force on the print head isapplied to only the wires, thereby keeping the wires under continualstress. This stress reduces the useful life of the wires. Moreover,free-standing wire heads leave scratch marks on paper due to the highpressure at the point of contact between the paper and the wire.Encapsulated wires do not scratch the paper.

Although in the above discussion of the print head and stylus the largerand smaller encapsulating tubes are formed from glass, any othernon-electrically conductive material may also be used for the tubes.However, glass is preferable due to its hardness and long life.

Although the method described above utilizes the same number of smallerencapsulating tubes as the number of wires, it is possible to use twoless tubes than wires. For example, only the central wire 74 of FIGS.10-14 need be encapsulated by a non-conductive tube 86 in order toelectrically insulate each of the wires 72, 74 and 76 from each other.

While the method of forming the print head discussed above is preferred,the encapsulated print head may be formed in other ways. For example,ribbons of tungsten may be placed on flat sheets of glass or othernon-conductive supporting material and fused or glued thereto. Also,glass or plastic may be injection or blow molded around tungsten wiresto form an encapsulated print head.

In summary, the encapsulated, solid block print head (FIG. 14) formedfrom the method illustrated in FIGS. 10-13 advantageously increases theuseful life of the printing wires, enables the print head to print inboth directions of traverse, allows the use of relatively small diameterwires to increase the fineness of the resolution of the printedinformation, and does not scratch the printing surface. The print headdescribed herein is useful in many different types of printingapplications, as for example in the facsimile machine discussed above,or computer terminal printers, medical instruments, chart recorders, X-Yrecorders, ticket printers, and similar electrostatic printingoperations.

I claim:
 1. A linear motor comprising:a movable element, a plurality ofelectrical coils connected to said movable element and movabletherewith, a plurality of longitudinal members each having a pluralityof magnetic elements spaced apart along its longitudinal axis, saidlongitudinal members guiding and supporting the entire weight of saidmovable element as it moves along said members, said electrical coilsand magnetic elements being arranged so that when said electrical coilsare energized magnetic interaction between said electrical coils andsaid magnetic elements causes said movable element to move along saidlongitudinal members, wherein the longitudinal extent of individualmagnetic elements is greater than the longitudinal extent of theelectrical coil.
 2. The apparatus of claim 1 further comprising meansfor selectively energizing each of said coils individually.
 3. Theapparatus of claim 2 wherein each electrical coil is mounted adjacent adifferent longitudinal member.
 4. The apparatus of claim 1 furthercomprising means for sensing the position of said movable element. 5.The apparatus of claim 4 wherein said sensing means comprises a timingfence that extends in the same direction as said longitudinal member andmeans mounted on said movable element for generating electrical signalsby illuminating said timing fence, whereby electrical signals aregenerated as said movable element moves along said timing fence.
 6. Theapparatus of claim 5 wherein said sensing means further comprises meansmounted on said movable element for detecting motion of said movableelement by the Moire effect.
 7. The apparatus of claim 1 wherein saidmagnetic elements are iron slugs.
 8. A linear motor comprising:a movableelement, a plurality of electrical coils connected to said movableelement and movable therewith, a plurality of longitudinal members eachhaving a plurality of magnetic elements spaced apart along itslongitudinal axis, said longitudinal members guiding and supporting theentire weight of said movable element as it moves along said members,said electrical coils and magnetic elements being arranged so that whensaid electrical coils are energized magnetic interaction between saidelectrical coils and said magnetic elements causes said movable elementto move along said longitudinal members, and means for sensing theposition of said movable element comprising a timing fence that extendsin the same direction as said longitudinal member and means mounted onsaid movable element for generating electrical signals by illuminatingsaid timing fence, whereby electrical signals are generated as saidmovable element moves along said timing fence.
 9. The apparatus of claim8 wherein said sensing means further comprises means mounted on saidmovable element for detecting motion of said movable element by theMoire effect.